Effects of heating on the air atomization characteristics of n-heptane
Based on the background of fuel cooling and heating atomization technologies,an investigation was conducted using the air-assisted spray heating atomization test bench and a digital coaxial holographic measurement system to explore the effects of heating conditions on the atomization characteristics of n-heptane and the evaporation of n-heptane in the spray jet.The results indicate that the improvement in atomization under the low air-liquid mass ratio(ALR=1.5)conditions and the significant reduction in the spray cone angle are brought about by the increase in n-heptane temperature.However,the influence of n-heptane temperature variation on the spray cone angle is not significant under the high ALR conditions.The elevation of n-heptane temperature results in a decrease in droplet density,viscosity,and surface tension,thereby reducing the required energy for breakup,promoting the secondary atomization of large particles,and leading to a significant reduction in the sauter mean diameter,with a reduction of up to 70 μm.Furthermore,the increase in n-heptane temperature reduces the latent heat of evaporation,making droplets easier to evaporate,thereby increasing the n-heptane vapor concentration in the spray.Under the condition of n-heptane temperature at 90℃,the n-heptane vapor concentration in the spray can reach 2.28%vol.
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